Tanning process.



"an ears OTTOKAR HENRY NOWAK, OF CHICAGO, ILLINOIS, ASSIGNOR TODERIVIIFORMA COMPANY OF AMERICA, A CORPORATION OF ILLINOIS.

TANNING PROCESS.

No Drawing.

NoWAK, a subject of the Emperor of Austria-Hungary, residing at Chicago,county of Cook, State of Illinois, have invented a certain new anduseful Improvement in Tanning Processes, and declare the following to bea full, clear, and exact description of the same, such as will enableothers skilled in the art to which it pertains to make and use the same.

My invention relates in general to the manufacture of leather and moreparticularly to an improved process of preparing and tanning hides andskins.

The primary'object of my invention is to provide a process for quicklyconverting hides and skins into leather which will not involve the useof mineral acids and which, consequently, will be free from theinjurious effects of the present so-called quick process.

A further object of my invention is to provide a tanning process thepractice of which will require comparatively little time, which willpreserve the texture of the hides and skins, and which will result in asoft,

firm, durable, and high quality of leather.

My invention generally described consists in employing in lieu ofmineral or other acids during the process of tanning sour milk wheywherein bacteria have been de veloped and which has been caused toferment for a sufiicient period to convert at least 1% thereof intolactic acid. This fermented sour whey and the process of maki ing thesame forms the subject of a separate i one of these'operations eventhough it be not employed in the remaining operations which go to makeup thecomplete process. However, the best results, both as to the speedand cost of the process and as to the character andquality of theproductare obtained Specification of Letters Patent.

Patented June 2'7, 1911.

Application filed June 14, 1905. Serial No. 265,282.

when the Whey is employed in each of the operations to which it isadapted, for the use of whey in an operation which is followed byanother operation wherein whey is again used greatly expedites andcheapens the latter operation because of the freedom of the skin or hidefrom acids which will act detrimentally to the bacteria in the whey.

In the step of unliming hides and skins I have found that by using evena liquor containing but little of the aforesaid whey a very heavilylimed hide or skin becomes so thoroughly saturated with the liquor inthe space of a fraction of an hour that no trace of lime remains, whileat the same time the hides and skins commence to plump without beinginjuriously affected.

In the step of pickling or preserving I have found that the aforesaidwhey, when added to the salt liquor, not only helps to preserve but,even at this stage of the process, helps to open the pores of the hidesand skins. I have also found that the step of plumping or swelling thehides orskins for holding the pores open to better receive the tanningliquor can be accomplished in a most satisfactory manner by using aliquor containing considerable of the aforesaid fermented sour whey inconcentrated form, the plumping commencing instantly and progressing inseveral hours to a marked extent. By concentrated fermented. sour whey Imean fermented sour Whey produced in the manner heretofore specifiedfrom which some of the moisture has been evaporated so as to increasethe density. This concentration may be effected in any suitable manner,preferably in the manner described in my aforesaid patent. The grain ofthe material becomes bright and rich, the gelatin is unaffected, and theexterior of the hide or skin remains plump or open for the reception ofthe tanning liquors. Moreover, the pores remain open and the plumpnessis retained for a considerable period thereafter, so that the final stepof tanning and filling can be accomplished successfully even though sometime elapse between it and the plumping operation.

In the final step in converting hides and skins into leather, namelythat of tanning and filling, a great improvement is effected 60 erablyadded to about 100 gallons of salt by adding to the tanning solutionsome of -the aforesaid fermented sour whey, as the required-bacteriallife is produced in the tanning liquor, not only in bark tanning, butmore noticeably in the so-called sweet liquor or extract tannage,comprising extracts of oak bark, hemlock, quebracho, chestnut, etc. Nomatter how strong the tanning liquor may be, the plump hides and skinsare filled in a short time and a leather produced of mellow andunsurpassed quality. Heretofore it has been impossible, in using anyconcentrated tanning extracts, which in their preparation have beensubjected to high temperatures, to obtain the desired bacterial action,on account of the and skins by leaving therein the gelatin, but

increasing the same through the added sugar of milk. The practice of myimproved process therefore obviates the necessity of treating the hidesor skins with glucose to give the leather greater weight as is now thecustom in the preparation of sole leather.

My invention may be utilized in various ways in tanning and may readilybe adapted to the various processes of treating hides and skins in themanufacture of all kinds of leather, and I therefore do not wish tolimit myself to any particular proportions of whey to be used in thevarious steps or operations of tanning processes. I have found, however,that in bating or unliming one pound of concentrated or 6 pounds of saidwhey in unconcentrated form added to approximately 1000 gallons ofwater, is sufficient for 100 pounds of raw hides or skins. Even largerquantities of whey will have no injurious effect and smaller quantitieswill also effect the desired result if given sufficient time. In thestep of pickling or preserving approximately one-half pound ofconcentrated or three pounds of unconcentrated whey of the characterheretofore specified may be used for 100 pounds of raw hides or skins inconnection with the required amount of salt; the whey being prefsolutionhaving a density of from 15 degrees to 16 degrees Baum. For plumping orswelling the hides or skins, either 3 pounds of concentrated or 18pounds ofunconcentrated whey produced in the manner heretofore specifiedmay successfully be used, the Whey being preferably added toapproximately 2000 gallons of either natural sour tanning bark liquor orsweet extract liquor. However, the said whey may be used without water'even when concentrated without injuring the hides or skins bydeteriorating the grain or affecting the gelatin, and will accomplishthe plumping very rapidly. In the tanning or filling step an addition ofthree pounds of concentrated or 18 pounds of the unconcentrated whey ofthe character heretofore specified in about 2000 gallons of tannicliquor is sufficient for the required fermentation, but a greater orless quantity may be used with excellent results.

I have found that the finest quality of leathers may quickly and cheaplybe produced by employing the said whey in each of the several stepsconstituting the tanning processes. The use of the aforesaid whey in anystep improves the tanning process and also the product but the finestproduct is obtained when the whey is used in all of the steps for thereason that there is in such case no need for employing any substancewhich will act injuriously to the gelatin in the hides or to the fiberof the hides. Furthermore when one of the steps is carried out in theold way and is followed by an operation wherein the said whey isemployed, there is apt to be a retardation of the latter step due to theinjurious effect upon the bacteria in the whey by substances which havebeen retained within the pores of the hides or skins from the previousstep.

That I claim:

1. In the art of manufacturing leather, the step of treating the hide orskin with a substance derived from milk which has been caused to fermentuntil at least 1% thereof has been converted into acid calculated aslactic acid.

2. In the art of manufacturing leather, the step of treating the hide orskin with concentrated whey which has been caused to ferment until itcontains at least 1% acidity calculated as lactic acid beforeconcentration, mixed with a quantity of such whey in unconcentratedform.

3. In the art of tanning leather, the process of treating the hide orskin with tanning liquors to which have been added concentrated wheywhich'has been caused to ferment until it contains at least 1% aciditycalculated as lactic acid before concentration, together with a quantityof such whey in unconcentrated form.

4. In the art of manufacturing leather, the process of treating hides orskins with a substance derived from milk which has been caused toferment until at least 1% thereof has been converted into acid.calculated as lactic acid in order to unlime the hide or skin;preserving the material in a In testimony whereof, I sign thisspecifisolution of salt liquor containing some of cation in the presenceof two-Witnesses. said substance derived from milk; again treating thehide or skin With said substance OTTOKAR HENRY NOWVAK' derived frommilk; and then treating the Witnesses:

hide or skin to a solution of tanning liquor GEO. L. WILKINSON,

containing said substance derived from milk. C. A. MULLEN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

